With the ongoing trend towards smaller, faster and higher performance electrical components, such as a processor used in computers, routers, switches, etc., it has become increasingly important for the electrical interfaces along the electrical path to also operate at higher frequencies and at higher densities with increased throughput.
In a traditional approach for interconnecting circuit boards, one circuit board serves as a backplane and the other as a daughter board. The backplane typically has a connector, commonly referred to as a header that includes a plurality of signal pins or contacts, which connect to conductive traces on the backplane. The daughter board connector, commonly referred to as a receptacle, also includes a plurality of contacts or pins. Typically, the receptacle is a right angle connector that interconnects the backplane with the daughter board so that signals can be routed between the two. The right angle connector typically includes a mating face that receives the plurality of signal pins from the header on the backplane and a mounting face that connect to the daughter board. Likewise, the header includes a mating face adapted to mate with the mating face of the right angle connector and a mounting face that connects to the backplane board.
As the transmission frequencies of signals through these connectors increase, it becomes more desirable to maintain a desired impedance through the connector to minimize signal degradation. A ground shield is sometimes provided on the module to reduce interference or crosstalk. In addition, a ground shield may be added to the ground contacts on the header connector. Improving connector performance and increasing contact density to increase signal carrying capacity without increasing the size of the connectors is challenging.
Some older connectors, which are still in use today, operate at speeds of one gigabit per second or less. In contrast, many of today's high performance connectors are capable of operating at speeds of up to 10 gigabits or more per second. As would be expected, the higher performance connector also comes with a higher cost.
When trying to design an electrical connector having a reduced pitch between signal pins, so as to obtain an electrical connector with a reduced size or with an increased pin density, the signal pins are made thinner and are therefore more fragile and likely to be bent or broken. When these electrical connectors are implemented in high-speed applications involving high transmission data rates, it is crucial to guarantee a high degree of electrical performance. However, the impedance and other important electrical properties of an electrical connector are dependent on the geometrical arrangement of the signal pins with respect to one another. Hence, it is challenging to design an electrical connector having a smaller pitch between its contacts, while guaranteeing high electrical performance.
Another problem, which might occur in electrical connectors, is that the contacts in the housing of the electrical connector, in particular the resilient parts that are located at the end of the electrical contacts, may be inaccurately positioned. This inaccurate positioning is considered a failure mechanism according to the electrical connector qualification tests used for telecommunication connectors such as Telcordia GR-1217-Core in the American market. This inaccurate positioning of the resilient part of the electrical contacts within one electrical connector can occur during production, handling, insertion, board handling, mating, etc. Furthermore, interferences may result that cause deviations from the contact normal force that has been originally designed. Moreover, the contact normal force may also decay with time due to stress relaxation or deformations of the resilient parts of the electrical contacts or deformations of the plastic connector parts of the housing. If the contact normal force is reduced to low levels, any additional decrease could be unacceptable and the contact normal force may reach critical minimum values.
In a high-speed connector, which supports high data rates and high frequencies, the design of the dielectric material surrounding the electrical conductors is crucial. Indeed, in order to enable constant electrical properties along the path of signals carried by the electrical conductors in the electrical connector, the dielectric properties of the material surrounding the electrical conductors should be as continuous as possible, and irregularities within the dielectric material should be avoided. In particular, introducing cavities in the over-molded material, which are filled with air, that has different electrical properties than the over-molded material itself, should be avoided as they introduce differences in the electrical characteristics within the dielectric material, thereby introducing irregularities within the electrical path of a signal, and therefore decreasing the electrical performance of the electrical connector.